1. Field of the Invention
The present invention relates to a display device, and more particularly, to a display device with integrated capacitive touch panel.
2. Discussion of the Related Art
A flat panel display (FPD) device is applied to various electronic devices such as portable phones, tablet personal computers (PCs), notebook computers, etc. Examples of the FPD device include liquid crystal display (LCD) devices, plasma display panels (PDPs), organic light emitting display devices, etc. Recently, electrophoretic display (EPD) devices are being widely used as one type of the FPD device.
In such FPD devices (hereinafter simply referred to as a display devices), LCD devices are the most widely commercialized at present because the LCD devices are easily manufactured due to the advance of manufacturing technology as well as realization of drivability through a driver and a high-quality image.
Instead of a mouse or a keyboard which has been applied to flat panel display devices in the past, a touch screen that enables a user to directly input information with a finger or a pen has been recently applied to the flat panel display devices.
Examples of an LCD device having a touch panel include an add-on type and an in-cell type.
An add-on type touch panel is manufactured independently from the panel, and is adhered to a plane of the panel. Also, the in-cell type touch panel is provided as one body with the panel.
Particularly, in an LCD device which is applied to portable terminals such as smartphones, a touch panel is integrated into a panel so as to slim the portable terminals. Such an LCD device is referred to as a display device with integrated touch panel.
FIG. 1 is an exemplary diagram illustrating a configuration of a related art display device with integrated touch panel, and particularly, is an exemplary diagram illustrating a configuration of an LCD device applied to a portable terminal such as a smartphone.
The related art LCD device with integrated touch panel which is applied to a portable terminal, as illustrated in FIG. 1, includes a panel 11 into which a touch panel 31 including a plurality of touch electrodes 30 is built, a display driver IC (DDI) 12 that controls a gate line and a data line which are formed in the panel 11, a touch driver IC (hereinafter simply referred to as a touch IC) 14 that drives the touch panel 31 which is provided in the panel 11, and a flexible printed circuit board (FPCB) 15 that is equipped with the touch IC 14 and electrically connects the display driver IC 12 to the touch IC 14.
The display device with integrated touch panel uses a time division driving method that uses the touch electrode 30 as a common electrode during an image display period, and during a touch sensing period, uses the touch electrode as a touch electrode.
Touch panels may be categorized into a self-capacitance type and a mutual type.
The related art display device with integrated touch panel into which the touch panel 31 using the self-capacitance type is built, as illustrated in FIG. 1, needs n×m number of touch electrode lines 32 in consideration of the number “n” of width-direction touch electrodes 30 and the number “m” of height-direction touch electrodes 30.
In this case, the touch electrode lines 32 is independently branched from the respective touch electrodes 30.
For example, in the touch panel 31 in which the number “n” of width-direction touch electrodes is 12 and the number “m” of height-direction touch electrodes is 20, as illustrated in FIG. 1, a total of 240 (=12×20) touch electrode lines 32 may be formed in the touch panel 31, and the 240 touch electrode lines 32 may be connected to the display driver IC 12.
The display driver IC 12 is connected to the touch IC 14 through 80 touch channel lines 16 which are formed on the FPCB 15. In this case, the display driver IC 12 connects the 240 touch electrode lines 32 to the 80 touch channel lines 16 by using a plurality of 3:1 multiplexers.
For example, the display driver IC 12 divides the touch sensing period into three sub-periods, and connects the 80 touch electrode lines among the 240 touch electrode lines to the 80 touch channel lines 16 at every ⅓ touch sensing period.
The related art display device with integrated touch panel has the following problems.
First, as described above, the related art display device with integrated touch panel includes the display driver IC 12 mounted on the panel 11 and the touch IC 14 mounted on the FPCB 15.
In this case, for example, as illustrated in FIG. 1, the related art display device with integrated touch panel includes an excessive number of touch electrode lines 32 (for example, 240 touch electrode lines 32), and needs the 80 touch channel lines 16 and the touch IC 14 having a large size (6×6 mm2), for electrically connecting the display driver IC 12 to the FPCB 15.
Therefore, the FPCB 15 applied to the related art display device with integrated touch panel has a bulky shape. For this reason, a process which mounts the touch IC 14 on the FPCB 15 or forms the touch channel lines 16 becomes complicated, and moreover, the manufacturing cost increases.
Second, as described above, an excessive number of the touch channel lines 16 and the touch IC 14 having a relatively large size are vulnerable to an external physical impact, and for this reason, touch ghost noise is easily caused.
Third, the touch IC 14 includes 80 pins. For this reason, there is a high possibility that an error occurs in a process of mounting the touch IC 14 on the FPCB 15, and thus, an error rate of the display device with integrated touch panel increases.